Although Bergen officials said the mumps cases were among the general population, Hudson County authorities are taking precautions with immigrant detainees. William O'Dea, a Hudson County legislator, said officials were acting on advice from a Bergen County warden to check immigrant detainees who arrived May 18 and were on the same flight as those taken to Bergen County.

"We isolated the individuals that came in on the flight so we can check them. We are examining them, isolating them until we examine them,'' O'Dea said. "So far, the ones that we have examined there have been no issues."

How is mumps transmitted?

Mumps spreads through direct contact with saliva or respiratory droplets from the mouth, nose or throat. It can be spread through:

Close quarters can make the disease more susceptible to spreading, according to the Centers for Disease Control and Prevention.

From Jan. 1 to late May, 42 states and Washington, D.C., had reported a total of 1,002 cases of mumps this year, according to the CDC.

The disease was greatly reduced once the mumps vaccine was introduced in 1989, but cases started increasing again in 2006.